The present invention relates generally to fluid cylinder assemblies, and more particularly to improvements in fluid cylinder and piston assemblies used on machinery. Of particular significance are the type used in the operation of marine vessels such as boats, ships, and the like. For example, Arneson-type marine outdrive systems that utilize fluid cylinders for trim and steering functions are described in U.S. Pat. Nos. 4,544,362, 4,645,463 and 5,667,415.
Fluid operated piston and cylinder assemblies are used in many forms and must be capable of continued reliable operation without failure. Typical applications include use in construction equipment, aircraft, watercraft, military vehicles, cranes and jacks. In many applications the cylinder assemblies are exposed to severe natural elements or other harsh conditions, and generally receive little attention or maintenance. Marine applications can be particularly harmful, as the cylinder assemblies may be partially to fully submerged in the water, and may be exposed to collisions with floating or submerged debris. Therefore, the cylinder assemblies must be sufficiently rugged to receive impacts, shocks, vibrations and external pressures without leaking or breaking, especially when used in marine applications.
A major drawback of present piston and cylinder assemblies is the presence of external fluid lines that provide fluid to and receive fluid from the cylinder. These lines typically extend from a port in the cylinder to a fluid pump, a reservoir or a valve assembly, and are typically constructed from reinforced rubber or from rubber conduit reinforced with braided metallic fibers. The external fluid lines may be subject to unclean environments, chemical exposure and prolonged heat and sun exposure. In some applications, such as construction equipment, the physical location of the fluid lines makes them vulnerable to being snagged by moving parts or other machinery.
In the harsh marine environment, the fluid lines may be exposed to sun and salt, and may even be partially or fully submerged in the water. In addition, the fluid lines may be cut or damaged if the watercraft strikes debris.
Additionally, exposed fluid lines can be the subject of sabotage or intentional severing in order to disable or damage the machinery.
Fluid cylinder assemblies may also be complicated and difficult to understand and repair. When maintained or replaced, they must be sufficiently understandable so that untrained personnel and relatively unsophisticated maintenance people may correctly repair or install them. Improper installation or maintenance may cause poor operation and premature failure. Therefore, it is desirable that the cylinders be made of parts that are simple and easy to construct, and thereby easy to build, as well as disassemble and service.
It is accordingly an object of the present invention to provide an improved cylinder assembly wherein the parts are more simply made and assembled than in devices heretofore available, and wherein the elements of construction are particularly well adapted to withstand the rigors of operation to which they are subjected.
One of the more specific objects of the invention is to provide a fluid cylinder assembly wherein the external hydraulic lines are eliminated by using internal chambers and channels that extend through certain elements of the apparatus.
A further object of the invention is to provide an improved cylinder and piston assembly including one or more linear position sensors capable of sending electronic signals to indicate the position of the piston relative to the cylinder. A further object is to provide an improved sealing and assembly mechanism for a piston rod in a hydraulic cylinder assembly wherein repair of the rod seal is easily accomplished and assembly and disassembly is more readily performed.
Other objects, advantages and features of the invention, as well as equivalent structures which are intended to be covered herein will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment thereof in the specification, claims, and drawings.
The present invention comprises an internally ported fluid cylinder assembly, wherein the cylinder may be mounted to a surface and may have the required fluid delivery lines pass through the surface at the mounting location, thereby eliminating the requirement of fluid lines that are external to the surface. A major advantage of the present invention is the capability of having multiple fluid delivery lines extend from a single end portion of the cylinder assembly parallel to the longitudinal axis of the assembly. Conventional fluid delivery lines typically extend from the cylinder perpendicular to the longitudinal axis of the cylinder.
While the present invention helps to prevent failure of fluid delivery lines, it also provides environmental protection upon fluid delivery line failure or breakage. Oil is commonly used within fluid cylinder assemblies for lubrication and operation. When a conventional fluid line fails, the oil contained therein may escape and cause environmental contamination. Because the present invention eliminates external fluid lines, failure due to environmental exposure, accident or sabotage is unlikely. If for some reason a fluid line should fail, any fluid leak will be contained within the machine or vessel and will not escape into the environment. In fact, a small internal reservoir may be designed into the machine or vessel to catch and contain any fluid escapement in the unlikely event of failure.
The present invention may incorporate internal linear position sensors, thereby allowing the precise extension of the cylinder assembly to be known. Linear position sensors within the present invention may also be installed without the requirement of lines or wires that are external to the machine or vessel.
Another advantage of the present invention is having multiple internal ports that provide the same change in volume of fluid per length of extension or retraction of the cylinder assembly piston. Thus, the cylinder assembly may extend and retract at the same speeds when a single motor effects the fluid delivery for both extend and retract operations.
An exemplary application of the present invention is associated with marine outdrive units, which are typically used on large and/or powerful marine vessels. A typical marine outdrive apparatus has a tubular drive shaft support casing secured to and extending rearwardly from the transom of a boat. The casing connects at its proximal end to the boat transom using a pivoting connection, such as a ball joint. The casing supports a drive shaft that extends from within the boat through the casing to a propeller located at the distal end of the support casing. A universal join means located along the drive shaft coincides with the pivot point of the ball joint. This allows the propeller and distal end of the casing to move along a spheroidal path relative to the ball joint while still receiving power.
The marine outdrive apparatus lends itself to the use of one or more fluid cylinder assemblies connected between the boat transom and the support casing to control movements in the horizontal plane, and one or more fluid cylinder assemblies to control movements in the vertical plane. Horizontal and vertical movement controls provide respective steering and trim control of the boat while the boat is underway.
Conventional cylinder assemblies used in a marine outdrive apparatus are subject to the drawbacks and limitations described in the Background of the Invention. The present invention eliminates fluid lines that are external to the vessel, thereby providing a longer operational life for the assembly, reducing maintenance requirements, providing greater security, reducing the possibility of environmental contamination and providing a more aesthetically pleasing vessel. The present invention also enhances safety by reducing the likelihood of loss of control over the vessel.
It is an object of the present invention to provide a cylinder design incorporating internal fluid channels and linear position sensor lines, thereby eliminating the disadvantages of having exposed fluid delivery lines and electrical cables that are external to the machinery or vessel.
Thus, it is a major object of the present invention to provide marine hydraulic steering and trim control cylinder assemblies that afford the advantages of presently utilized cylinders but eliminate the danger of damaging fluid lines due to exposure, intentional severing or by contact with debris.
It is an object of the present invention to provide fluid cylinders that may pivot as required in any direction or degree, and have an extension length that is required by the application for which the specific embodiment of the invention is used.
It is an object of the present invention to provide appropriate seals for proper sealing of all internal porting and passageways required to isolate the respective extend and retract functions of the cylinder.
It is an object of the present invention to provide means to isolate linear position sensor technology integral to the internal porting and still be capable of full functionality of both the cylinder assembly and the position sensor.
It is an object of the present invention to provide proper porting through an end section of the cylinder assembly and to provide proper internal channels and chambers for the unrestricted flow of fluid for both extend and retract functions of the cylinders and to obtain necessary cycle times.
It is an object of the present invention to provide proper means to seal the cylinder mount to the mounting surface, thereby preventing any external matter or fluid from entering the vessel, and also preventing any cylinder assembly fluid from escaping from the vessel into the environment.
It is an object of the present invention to provide cylinder elements capable of reliably and continuously withstanding the required loading and internal and external pressures, while at the same time providing adequate and proper internal chambers and channels necessary to accomplish operation of the assembly.
It is an object of the present invention to provide external anti-rotation devices to prevent any fluid cylinders from rotating during operation, which could cause attached cables and fluid delivery lines to twist and fail prematurely.
It is an object of the present invention to provide an aesthetic and compact design with the ability to accomplish all functions and operations of a conventional fluid cylinder assembly without the need for fluid delivery lines that are external to the surface upon which the cylinder assembly is mounted.